This application claims the priority of German patent application 196 43 222.7, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a lift body having a variable camber.
In order to adapt the lift and the flow resistance of a body around which a flow takes place to different environmental conditions and to optimize this lift and flow resistance, various arrangements and processes are known. In the case of commercial airplanes, the profile camber is changed, for example, by the kinematic displacement or rotation of separate flaps of the wing.
As a result, gaps and hollow spaces occur in the skin of the airplane wings. The wing body itself does not change its shape in this case.
From U.S. Pat. No. 3,109,613, an arrangement is known in which aerodynamic properties, particularly of lift surfaces of airplanes, can be influenced by a change of the profile shape or of the camber. The changing of the profile shape is achieved by a multisection, crankshaft-type structure in the interior of the airplane wing, in which case, via different bearings, a vertical displacement of webs takes place in the interior of the airplane wing. By means of a piano-hinge-type bearing, the webs are connected in an articulated manner with the suction-side or pressure-side skin of the wing. By the rotation of the shaft, the profile shape is bent piece by piece, whereby a quasi-continuous deformation of the airplane wing structure is achieved.
The described processes and devices have the disadvantage that the joint structures result in very high constructional expenditures, and high actuator forces must be implemented for moving the structures in order to permit a sufficient change of the camber.
Furthermore, the arrangement described in U.S. Pat. No. 3,109,613 is to be implemented with high mechanical expenditures. By means of this arrangement, a high stiffness can be implemented only by a high increase in weight.
In contrast, there is a need for a lift body in which the flow-around characteristics are improved by the continuous deformation of a light, stiff and low-friction adjusting device.
This and other needs have been met according to the present invention by providing lift body having a variable camber, particularly airplane wings, having a fluidically favorable profile which at least at times generates a lift or transverse driving force, having a structure which is for the most part hollow, is elastically deformable at least downstream of the largest profile thickness and has several web-type connections between the suction-side and the pressure-side skin, as well as having an integrated adjusting device comprising one or several dimensionally stable adjusting bodies which can each be rotated about a defined axis and are in a mechanical operating connection with the skin areas to be deformed, characterized in that in the deformation range of the lift body structure, each adjusting body 7 has a curved conical shape whose local cross-section corresponds to the profile thickness at the respective point; and each adjusting body 7, at least in areas, by means of a line contact is in a direct contact and/or by way of at least one thin friction-reducing layer 11 is in an indirect contact with the skin 3, 4 of the lift body.
The invention is based on implementing via an integrated adjusting device in a lift body a variable and continuous camber change with a smooth, constant profile contour without bends. The adjusting device has at least one essentially single-section adjusting body. Preferably, several adjusting bodies are arranged in parallel with respect to one another. A camber change of the top side as well as of the bottom side of the profile along the chord in the negative direction (negative camber) as well as in the positive direction (positive camber) between a fixed spar and the wing end edge or also the front edge is permitted as a result of this integrated adjusting device. It is a special advantage that also an adjustment differentiated with respect to the span width can be implemented for the positive camber and the negative camber.
The previously existing problem of adapting the contour, for example, of an airplane wing, which is constructed in the known rigid rib construction, to a flow profile is addressed by the present invention without the occurrence of bends, cracks or gaps in the profile of the skin. The flow characteristics of the lift body are therefore considerably improved.
It is another advantage of the invention that the geometrical moment of inertia of the arrangement according to the invention is significantly larger than the geometrical moment of inertia of arrangements known from the state of the art. High stiffness requirements can be met without having to tolerate a large increase in weight. It is particularly advantageous that, because of the large geometrical moment of inertia, the adjusting body need not be constructed of a massive material, particularly of metal, but hollow bodies and preferably light-weight materials can be used, particularly preferably fiber-reinforced materials. This minimizes the weight increase of an airplane wing which is equipped with the adjusting device according to the invention.
The continuous camber change without buckling in the skin is particularly protective of the material and prevents a premature material fatigue. The pressure-side and the suction-side skin is connected with the rigid forward part preferably via a threaded connection. The other skin side is not supported or can be provided with a linear bearing. This provides the skin structure with a flexibility which protects the material, and reduces the deformation forces.
The bearing of the adjusting body, particularly in the rigid forward part of the lift body, permits a variation of the camber of the lift body also in the case of aerodynamic stress.
It is advantageous to cause the rotation of the adjusting body via a linear drive which is applied to the adjusting body in a point-type manner. Also under an aerodynamic load, the course of the moments for the adjusting body has the result that, despite changing angular positions, the actuator must always apply approximately the same tensile force which, in addition, is relatively low because of the transmission ratio of the arrangement.
It is particularly advantageous that the lift body can be constructed in a simple and maintenance-friendly manner. The skin can easily be removed, and the adjusting device is freely accessible.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.